In the US it's often done by eyewitness testimony, statistical calculation, even undercover sting operations if necessary (easy to get a warrant for the business records, based on that behavior), subpoenaed accounts, etc etc etc. That's a lot of trouble, of course, but people who would otherwise suffer the consequences will go to that trouble. In the mortgage lending business, one common setup was to match pairs of people identical except for race, and send them into lending offices alternately.
You keep overlooking the fact that this is a reality you are talking about - this situation exists, in the US, right now. It's not speculation.
Wow. That's really totalitarian.
And, no, reality is not the question. The degree of totalitarian control of the people in America is interesting side information, but nothing more, because the question discussed is the conceptual differences between two ideologies, namely libertarianism/classical liberalism on the one hand, and American liberalism on the other hand. I think there is a big difference, and have found a lot of particular differences. But, ok, once the American liberal feels comfortable in actual America, and America has, in essential points, totalitarian mind control, this would be an additional argument for big differences.
No, I rely on demonstrated economic reality. They fail whether their proponents want them to and think they should or not - no sense involved.
I said "common sense" instead of "economic theory" simply because we hardly will agree about most parts of economic theory, but about this particular question I think there is agreement.
So now you have defending civil rights and liberties defined as totalitarian government, and must invent an entire mythology of "lawsuit by almost everybody for almost nothing" to back the silliness up. And all because you cannot handle physical reality in your theory.
I was born and lived a long time in some totalitarian state (ok, post-totalitarian would be more accurate, the hard totalitarian time was already over), so I know very well that there is a big difference between real liberties and the "liberty" as used in the totalitarian propaganda. And, by the way, the "economic rights and liberties" have been explicit part of that propaganda too. With the classical discrediting of liberal notions of liberty as the "same right for the homeless and the millionaire to sleep under the bridge".
If I give somebody a credit or not is a very subtle decision, and for reasonable people it depends on a very subtle thing, like personal trust. What you have described means that one is not allowed to rely on a personal feeling of trust, given that it is this vague personal feeling which often makes the difference between people who look equal in their records. Once you can be penalized for this, this means you can be penalized for almost nothing. This is nothing I invent, but you presented it. I interpreted it, based on libertarian principles and own experience with communist ideology.
If that is your motive, the matter was settled by my response (If they are behaviors that interfere with other people's civil rights and liberties, they would be restricted to the point they did not do that. If they aren't and don't, they would be ignored by a liberal State. So?) - and that's done with.
Fine that you have ignored my implicit question behind, namely "If you, instead, think, say, that it is part of civil liberties to visit Holy Places of other religions to urinate and masturbate, and therefore this should be, of course, allowed and protected by the government, the idea to bring in religion has not reached its aim." Of course, this choice of an example was polemical, but it is a question of principle, because there is not much conceptual difference between a Holy Place of some religious belief and a gated community.
And once again: in reality they did, do, and would again. In fact.
Because there was no such disadvantage as you imagine. Quite the contrary.
Indeed, for small firms there is a chance to survive because one discriminates against some customers. A motel or a bar, where different customers see each other, becomes more attractive to white racists customers if it excludes blacks. So, the loss because of the black customers may be overcompensated by additional income from white racist customers. But for this case of a small firm in a predominantly white racist environment the techniques I have described would work - except in the case of a totalitarian mind control police state. (Which, if one follows your description, already exists in the US.)
Don't forget, your economic point was that this does not work for big firms. "It turns out that doesn't work for entire communities, though, dealing with strangers as customers in roadside businesses, and so forth. So no problem - civil rights of blacks are safe, no government intervention necessary."
Here I agree. Big firms may be controlled easily in a police state. Only small firms can find ways to circumvent police control.
So: change your theory. It conflicts with the facts.
Seems, we need a little excursion into elementary scientific methodology.
The part of the theory we are talking about cannot conflict with the "facts", it is about how they have to be interpreted. How can a theory, which distinguishes just law from unjust law, be in conflict with some facts? All the facts can change is the classification of the laws in some particular state. Is actual US law just or unjust? If the facts about US law change, the answer can change. But there cannot be a conflict between the theory of just law and facts. You have to add something else - say, a claim that actual US law is just. Then you can have a conflict between the theory, this claim, and the facts.
This additional hidden claim in your argumentation seems to be that actual US law, say, after 8 years of liberal hero Obama or so, is, at least in essential parts, just law. But this, if present, would characterize only the American liberal notion of just law. And if it appears that from point of view of classical liberal/libertarian theory actual US law is unjust, totalitarian law, all we have found would not be that classical liberal/libertarian theory is in conflict with facts, but that classical liberal/libertarian theory is in conflict with American liberal theory as well as with the claim that actual US law is just.
This is just a test. I think you are able to understand this point. If you ignore it, and continue your "It conflicts with the facts" nonsense, you degrade yourself down to the joepistole level.
EDIT - fixed quote tags, per request of poster - Kittamaru